The usual permutation lock found on lockers in schools and the like has a protruding cylindrical knob which is turned to rotate the numbers on the skirt of the knob in the sequential combination required to open the lock. Most such locks have the lock mechanism including the permutation discs inside the knob. Students have found a well placed kick on the side of the knob will break the knob, destroy the lock and open the locker for inspection. Permutation locks made according to my U.S. Pat. No. 3,395,557 with the lock works including the permutation discs located behind the door were provided with protruding cylindrical knobs which could be destroyed with a well placed kick.
The object of this invention is to provide a permutation lock which is not vulnerable to a kick.